Linkage device for mounting swather header

ABSTRACT

A levelling mechanism for use a in lift system of a windrowing machine of the type including a tractor unit and a swather header to permit the use of a grain header which is held suspended above the ground rather than a hay type swather header which normally engages the ground during cutting. The type of lift systems used in some known hay windrowers include a pair of lift assemblies each of which has a single action lift cylinder. The two cylinders are supplied from a common supply line, and because the moving lift components of the two assemblies are individually activated by their respective cylinders the suspended grain header does not remain levelled under certain conditions, such as if there is a build up of greater crop weight at one end relative to the other. The present levelling mechanism includes a torsion bar carried at the front of the tractor unit, the torsion bar having radial arms at opposite ends which are connected to the moving component of the adjacent lift assembly so as to resist movement of the moving components out of unison, thus keeping the head level under normal cutting conditions.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a levelling mechanism for use in maintaining aswather header level, particularly the header as used in a floatingcondition during the swathing operation.

2. Description of the Prior Art

There are marketed swathers which are of the self-propelled types,commonly termed "windrowers", and such machines include a tractor unitand a header. The tractor unit known as a windrower tractor is providedwith a lift mechanism at the front, including a hydraulic system andlinkage arrangement, for raising the header from a lowered operatingposition to a raised inoperative position free of the ground.Self-propelled windrowers of this type are manufactured and sold, forexample, by Ford New Holland under the trade-mark SPEEDROWER, Models2450 and 2550, and are specially designed for cutting, conditioning andwindrowing hay. As the cutting of hay crops requires that the cut bemade close to the ground, the header is provided with skid shoes whichallow the hydraulic system to be actuated in a manner to move the headerto the lowered operating position wherein the skid shoes ride on theground and thus support the header with the cutting blade slightly abovethe ground level. As will be described in more detail below, the liftarrangement for such hay headers includes a pair of transversely spacedheader lift assemblies, each including a single acting cylinder and aspring system for partially counteracting the weight of the header inthe lowered position. When the cylinders, which are connected to acommon hydraulic line, are actuated so that pressurized hydraulic fluidis provided from the line to cylinders, the header is raised. Becausethe header is carried by the transversely spaced skid shoes whencutting, levelling of the header is not a concern as the lift assemblieseffectively operate independently. In fact, because the spaced skidshoes follow the ground contour, one end of the header can follow theground to a higher level than the opposite end, and the hydraulic fluidsimply flows from the cylinder which is being forced to a contractedcondition to the other cylinder which is moving to a more extendedcondition.

Because a major cost of the windrower is in the windrower tractor unit,it is advantageous to be able to use the windrower tractor for otherfunctions, including that of swathing grain crops. It is preferable,however, to utilize a different type of header for swathing grain,namely one which does not include conditioner rolls and which transfersthe cut grain to a windrow opening of the header by a travelling beltrather than an auger feed. Also, because it is necessary to cut a graincrop at a greater distance from the ground, a grain swather does notride on skid shoes but is held suspended at a higher elevation. With theabove described lift assembly commonly provided on the hay windrower,such as the * SPEEDROWER and similar windrowers * - trade-mark sold byother agricultural equipment manufacturers, the grain crop swather cannot be readily held in a level condition while swathing with the headerheld suspended above the ground because when the pair of hydrauliccylinders are not operated to their fully lifted positions, the fluidcan be displaced from one lift cylinder to the other, depending on whichend of the header is heavier.

SUMMARY OF THE INVENTION

It is the object of the present invention to provide a levellingmechanism which can be utilized on a windrower tractor to enable thetractor to be used with a grain swather header and to carry the headerin a suspended swathing condition.

Accordingly, the present invention resides in a levelling mechanism foruse in a lift system on a tractor for supporting a swather header, thelift system being of the type including a pair of lift assemblies eachhaving a hydraulic cylinder one each being pivotally connected at oneend to a fixed frame member and at an opposite end to a movable liftmember connected to the header, the cylinders, when actuated,individually moving the lift members for raising the header between aheader operative position and a header raised position. The levellingmechanism of the present invention includes mounting means forattachment to a front portion of the tractor, and a transverselyextending bar carried in the mounting means for at least partialrotational movement about a longitudinal axis of the bar. A pair of armsare each rigidly affixed at their inner ends of the bar at spacedlocations along the bar, each arm projecting radially from thelongitudinal axis of the bar. Means interconnect one each of the arms toone of the moving lift members for resisting movement of said movinglift members out of unison.

It is desirable that provision be made in a header lift system to allowone end of a mounted header to raise relative to the other end if theend is pushed upwardly, such as when the one end rides up on an obstacleor a raised portion of the ground. Thus, according to one aspect of theinvention, the bar may be in the form of a torsion bar selected inrelation to the lift system and the header to torsionally flexsufficiently to allow the arms to flex out of unison in response to asignificant force, thereby allowing the raising of one end of the headerrelative to the opposite end of the header.

In a specific embodiment of the invention the means interconnecting atleast one of the arms of the levelling mechanism to one of the movinglift members is a linkage including means for selected adjustmentpermitting effective relative movement of the moving lift members out ofunison for the purpose of achieving initial levelling of the header.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which show an embodiment of the inventionas an example,

FIG. 1 is a perspective view of the front portion of a tractor equippedwith a commonly used form of a lift system designed for a hay windrowerand equipped with the levelling mechanism of the present invention;

FIG. 2 is a top view of the tractor portion and lift system of FIG. 1,and showing the mid-portion of a grain swather header mounted thereon;

FIG. 3 is a top view on an enlarged scale showing part of one of thelift assemblies in the lift system of FIG. 1 and including one end ofthe levelling mechanism of the present invention;

FIG. 4 and FIG. 5 are cross section views as seen from the line 4--4 ofFIG. 2 showing the header in a lowered position and in a raisedposition, respectively; and

FIG. 6 is a view as seen from the line 6--6 of FIG. 2, but enlarged, andwith the header removed for the sake of clarity, showing in phantom thelift assembly and levelling mechanism in the raised position as well.

DESCRIPTION OF A PREFERRED EMBODIMENT

In the drawings, in which like reference characters denote likereference elements as referred to herein, there is generally denoted bythe reference character 10 the levelling device or mechanism of thepresent invention. The levelling mechanism 10 is shown mounted on thefront portion 11 of a windrower tractor 12 equipped with a lift system13. The lift system 13, which is shown as being of the conventional typeused in the windrower tractor of the above identified * SPEEDROWER ofFord New Holland, includes a pair of lower lift arms 14 supporting aswather header 15 (FIG. 2). The swather header 15 is of the type used incutting and windrowing grain, and accordingly it is carried entirely bythe tractor 12 and does not ride on skid shoes as does the normal hayheader of the *SPEEDROWER windrower. The lift arms 14 have forward endportions which extend under the header for supporting the header, andwhen used in conjunction with the grain header 15 and when the liftsystem 13 incorporates the leveling apparatus 10 of the presentinvention, the lift arms 14 entirely support the header 15 during whatmy be termed a lowered swathing or operating condition.

The grain header 15 includes a pair of lower, forwardly projecting framemembers 16 beneath the table thereof which are provided with bracketmeans 18 for engagement with the forward end of the transversely spacedlift arms 14. The framework of the header includes an upper,transversely extending frame member 17 which extends the full length ofthe header, and it is connected to a frame member at the front portionof the tractor 12 by way of an upper link 20, the connection at thefront of the lift arms 14 and the link 20 thus in effect providing athree point connection between the header and the tractor. The upperlink 20 is pivotally connected at its forward end to the upper framemember 17 by * - trademark way of a bracket 21 affixed to the framemember 17 and at its rear end to the tractor by way of a bracket 22affixed to a frame member of the tractor 12. Extending entirely acrossthe front edge of the header 15 is a sickle bar 23 for cutting the grainwhich is then carried by a belt (not shown) to a swath outlet of thegrain header 15 (not shown). As indicated above, in grain swathing thegrain may be cut at somewhat greater height than hay, and the sickle baris thus positioned above the ground, its position being controlled bythe machine operator by setting the retracted position of cylinders 24of the lift system 13, as will be described in more detail below.

In the lift system 13 of the tractor 12 there is provided a pair oftransversely spaced lift assemblies 25 of like construction, eachincluding a downwardly depending rigid frame member 26 which is affixedto the framework of the tractor. As shown in the drawings, a lug 28which is integral with the rear portion of the forwardly projectinglower lift arm 14 is pivotally connected to the lower part of the framemember 16 by way of a pivot pin 27. The axis of pivot of the lift arm 14provided by the pin 27 extends transversely relative to the direction oftravel so that each arm can pivot up and down in a vertical plane forthus lifting and lowering the header 15. The lower cylinder end of thecylinder 24 is pivotally connected to the frame member 26 by a pivot pin30. The cylinder 24 has a piston rod 31 extending from the upper end andit is connected to a bracket 34 which is affixed to the upper end of alift link 37 by way of a pivot pin 33. The upper arm 32 has a lower part35 which has a rear portion thereof pivotally connected to the framemember 26, and an upper part 36 which projects upwardly and forwardly.The parts 35 and 36 are connected together so as to pivot as a unitrelative to the frame member 26 about a transverse axis which isparallel to the axis of pivot of the lower lift arm 14. The bracket 34of the lift link 37 is pivotally connected at its upper end by way of apivot pin 40 to the lower part 35 of the upper arm 32 and at its lowerend, the lift link 34 is pivotally connected to a lug 41 affixed to thelift arm 14 by way of a pivot pin 42. A pair of parallel springs 45 arepositioned between a spring support member 43 at their rear end and atransverse pin 44 at their forward ends, the pin 44 extending throughthe outer end portion of the upper part 36 of the upper arm 32. Thesprings are in tension when the header is in a lowered condition as willbe described further below.

The pair of lift cylinders 24 are each of the single acting type whichare connected to a common hydraulic line (not shown) which receivespressurized fluid through a control valve located in the cab of thetractor. The line communicates with the outer end of each cylinder sothat the admission of the pressurized fluid forces the piston rodstowards or fully to the extended position as shown in phantom lines inFIG. 6 which represents a fully raised position of the header. In thefully raised position the upper arm 32 is allowed by the expandedcylinder to turn in a clockwise direction, as seen in FIG. 6, and theexpanding cylinder also pulls up the lift link 37, this action providingthe upward force on the lift arm 14 carrying the head. The turning ofthe upper arm 32 in this direction allows the springs 45 to contract,and in fact, the spring action by contraction assists in raising theheader 15. When the operator of the machine actuates the control valvein the tractor cab to lower the head to an operating position, fluid isallowed to flow back from the outer ends of the cylinders 24 to thehydraulic reservoir as the weight of the header 15 pushes the lift arms14 downwardly. When the skid shoes of the header of a normal hayswathing header of the type for which the lift system has been designedengage the ground, the tension under which the springs have been placedby the lowering action control the weight of the header actually carriedby the skid shoes. In the design just described, where the liftassemblies are independent of each other, it is apparent that if one endof the header rides over a raised portion of the ground, that end isfree to raise to a higher level than the opposite end of the header, thefluid remaining in the outer end of the cylinder at the lower end beingfree to flow to the outer end of the cylinder at the higher end via thecommon source line.

As previously described, the lift system described to this point is notin itself suited for use with a grain swathing header which ispreferably supported solely by the lift system above the ground in thatthe independent lift assemblies are not capable of maintaining the headlevel. For example if a greater weight builds at one end duringswathing, the weight will cause the end to be pushed downward and thefluid in the outer end of the cylinder 24 on the side corresponding tothe heavier weighted end can simply displace to the other cylinder viathe common supply line, thus permitting the opposite end to riserelative to the lower end. Accordingly, the principle purpose of thelevelling mechanism 10 of the present invention is to ensure that thelift arms of the two Separate lift assemblies 25 normally function inunison. In the illustrated embodiment of the invention, this isaccomplished by ensuring that the upper arms 32 which are movingcomponents of the two lift assemblies move substantially in unison undernormal operating conditions.

The levelling mechanism 10 includes an elongated bar 50 which extendtransverse to the direction of travel and is slightly shorter that thedistance of the spaced lift assemblies 25. The bar 50 is mounted in apair of brackets 51 which are designed for attachment to a frame portionat the front of the tractor. The brackets 51 have journal portions 52 toprovide aligned bearing for supporting the bar 50 for at least limitedrotation relative to the stationary brackets. A pair of arms 53 areaffixed to opposite ends of the bar 50 and project radially relative tothe longitudinal axis of the elongated bar 50. As can be seen in FIG. 1,for example, a pair of reinforcing flanges 54 are provided between thebar 50 and the sides of the arm 51 for strength purposes. Pivotallyconnected to the outer end of each arm by way of a pivot pin 55 is alink 56 which is connected to the upper part of the upper arm 32. Theconnection to the arm 32 is accomplished in a manner to effectivelypermit adjustment of the length of the link 56. An L-shaped bracket 57(FIG. 6) is affixed, such as by bolting, to the side of the upper part36 of the upper arm so as to provide a lug 60 which is aligned on aradially line extending from the axis of pivot of the upper arm 32,which pivot is coaxially with the axis of the bar 50. The lug 60 isapertured at a distance from the axis of the pivot of the upper armequal to the distance of the axis of the pivot pin 55 from the axis ofthe bar 50, and the outer end of the link 56, which passes through theaperture of the lug, is threaded. Thus two lock nuts 61 are screwed ontoto threaded portion on either side of the lug 60. By loosening the nut61 on the outer end of the link 56, for example, and then threading outthe nut 61 on the inner side of the lug 60, the effective length of thelink can be increased.

When the grain swather header 15 is initially mounted on the tractor 12,by engaging the lifting arms 14 with the bracket means 19 of the headerand the connecting link 20 between the brackets 21 and 22, the header 15is initially raised, and by adjusting the effective length of one orboth of the links 56 at the opposite end of the bar 50, the header canbe levelled as between the opposite ends thereof. When swathing is to bestarted, depending on the condition and type of the grain crop to beharvested, the header is lowered to set the desired position of thesickle bar 23 above the ground by allowing evacuation of an amount ofthe fluid from the lower ends of the single acting cylinders 24. Thelowering of the header will stretch the springs 45 of both of the liftassemblies 25 in the usual manner, and at the lowered position, thesickle bar will remain parallel to its initially levelled position.During operation, regardless of weight distribution along the length ofthe header, it will not vary substantially from the initially sethorizontal position due to the fact the bar 50, while turning to allowthe raising and lowering of the pivoted upper arms 32 of the two liftingassemblies 25, ensures through the connection of the set links 56between the arms 53 and the upper arms 32, that the upper arms 53 of thetwo lift assemblies pivot in unison.

The bar 50, while being designed to provide sufficient resistance totwisting about its longitudinal axis to normally prevent anysubstantially deviation of the head from its initially set horizontalcondition, also preferably functions as a torsion bar to allow turningof one arm 53 relative to the other under circumstances which establishhigh forces. Thus, in the event one end of the header engages anobstacle such as a raised portion in the ground, the header will bepermitted to deviate from the level. Under such a circumstance, therelative turning of the arms 53 due to the torsional action of the bar50 permits limited movement of the two upper arms 32 which in turnallows the header to raise at one end and thereby clear the obstaclerather than place undue stress on the header 15 and/or parts of the liftassemblies 25 which could cause damage.

Various alternatives may be made to the above describe embodiment of theinvention by those skilled in the art without departing from the spiritof the invention as defined in the appending claims. For example, whilethe arms 53 of the bar 50 are shown as being attached by links 56 to theupper arms 32, the arms 53 could be connected to other moving componentsof the lift assemblies 25 to ensure movement of the lift arms 14 inunison under normally operating conditions. The arms 53 could beconnected, for example, by a linkage means directly to the lift links 37or the lift arms 14. Also, while it has been explained that the bar 50is designed to function as a torsion bar to allow the header to deviatefrom its normally set leveled condition in the event an unusually highforce is applied to the header, the bar could be designed to resist eventhe higher forces tending to turn one arm 53 relative to the other.Instead there could be provided other resilient means, such as onelocated between the link 56 and the upper arm 32 to allow some movementof the upper arms 32 relative to each other in the event of theoccurrence of an unusually high force. It would further be obvious toprovide means other than the threaded links to achieve the initiallevelling of the header for presetting the position of a moving part ofthe lift assembly relative to the arms of the bar 50.

What I claim is:
 1. A levelling mechanism for use with a lift system ina tractor for supporting a swather header,said lift system being of thetype including a pair of lift assemblies each having a hydrauliccylinder, one each being pivotally connected at one end to a fixed framemember on said tractor and at an opposite end to a movable lift memberconnected to the header, said cylinders when actuated individuallymoving said movable lift member for raising said header between a headeroperative position and a header raised position, said levelling devicecomprising: mounting means for attachment to a front portion of saidtractor; an elongated torsion bar extending transversely to thedirection of travel and carried in the mounting means for at leastpartial rotational movement about a longitudinal axis of the bar, a pairof arms each rigidly affixed at inner ends of the bar at spacedlocations along the bar, each arm projecting radially from thelongitudinal axis of the bar; and means for interconnecting one each ofthe arms to one of said moving lift members, said torsion bar providingsufficient resistance to twisting about its longitudinal axis to resistmovement of said movable lift members out of unison and being selectedin relation to the lift system and said header to torsionally flexsufficiently to allow said arms to rotate out of alignment in responseto a significant force raising one end of the header relative to theopposite end of the header.
 2. A levelling mechanism as defined in claim1, wherein said means interconnecting at least one of said arms to oneof said moving lift members is a linkage including means for adjustmentto permit effective relative movement of said moving lift members out ofunison for the purpose of achieving initial levelling of said header. 3.In a windrowing machine including a tractor unit, a swather header, anda hydraulic lift system carried at a front portion of said tractor unitfor supporting said header and selectively moving said header between alowered operating position and a raised position;said lift system havinga pair of transversely spaced lift assemblies carried at opposite sidesof the front portion of said tractor unit, each assembly including aframe member affixed to said tractor unit, a forwardly projecting, lowerlift arm having a forward end engaging and supporting said header, saidlift arm being pivotally connected adjacent a rear end to said framemember, an upper arm pivotally connected to said frame member andconnected to said lift arm by a lift link, a hydraulic cylinder meansbeing connected to a pressurized fluid supply line and being pivotallyconnected between said frame member and said lift link for raising saidlink and swinging said upper arm to a header raised position onadmission of a pressurized fluid to one end thereof, the supply line ofthe cylinder means of both lift assemblies being connected to a commonhydraulic supply line: a levelling mechanism comprising; a bar carriedin mounting means attached to said front portion of said tractor, saidbar extending transversely between said lift assemblies and being atleast partially rotatable about its longitudinal axis within saidmounting means; a pair of arms affixed at inner ends thereof to said baradjacent opposite ends of bar, said arms each having outer ends spacedradially outward of the longitudinal axis of the bar; linkage meansinterconnecting one each of said arms to the upper arm of each liftassembly for resisting movement of said upper arms out of unison,whereby said lift arms are restricted to substantial unison movement intheir support of said header.
 4. In a windrowing machine as defined inclaim 3, wherein the torsional resiliency of said bar in said levellingmechanism is selected to permit torsional flexing of said bar inresponse to forces applied to said header of a value greater than thoseoccurring due to weight distribution on said header whereby said headeris permitted under extreme conditions to move from a preset levelcondition.
 5. In a windrowing machine as defined in claim 4, wherein thelongitudinal axis of the bar in said levelling mechanism is on a commonline extending through the axis of pivot of the upper arms in said pairof lift assemblies.
 6. In a windrowing machine as defined in claim 4wherein said linkage means between the outer end of at least one of eacharms of said bar in said levelling mechanism and the upper arm of therespective lifting assembly is of adjustable length for permittingadjustment of the distance between said arm and the upper arm of thelifting assembly whereby initial levelling of the header may be set. 7.In a windrowing machine as defined in claim 6 wherein said upper arm ofeach lift assembly has an upper portion, and each lift assembly furtherincludes tension spring means extending between said upper portion and aframe support means on said tractor unit for applying an assisting forceto said upper arm in a direction of lift of said header, and whereinsaid linkage of said levelling mechanism extends between the outer endof said arm of said bar in said levelling mechanism and a connectingmeans on the upper arm of the respective lift assembly.
 8. In awindrowing machine as defined in claim 7, wherein said connecting meanson said upper arm includes a lug affixed to said upper portion, said lughaving an aperture therein, wherein said linkage means includes a linkpivotally connected at one end to said outer end of said arm of said barin said levelling mechanism and having an opposite end extending throughsaid aperture in said lug, said opposite end of said link beingthreaded, and wherein locking nuts are threaded onto said threaded endto position the extent of said link extending through said opening,whereby the effective length of said link between said arm and saidupper portion of said upper arm of the respective lift assembly isadjustable.